The compounds to be synthesized in this project are known or suspected metabolites of carcinogenic polycyclic hydrocarbons which are urgently needed in carcinogenesis research. Many of the compounds are relatively unstable and a high level of synthetic skill and experience is required for their preparation. Compounds synthesized in this laboratory in the current and previous years of this contract were submitted to NCI which has supplied samples to numerous investigators in the scientific community. Work in carcinogenesis research has been productively stimulated by the availability of these compounds, and a number of the significant recent advances in this field were achieved with compounds prepared in this program.